11. What is a member? And if an object has a member, how do you access it?
12. So, we have a method with no dot. Come up with an example: myObject.doSomething(). What happens when you leave out the dot? Remember that the compiler is stupid. It can only handle what you feed it. It doesn't make stuff up.
13. Lots of code, but we're only interested in str1. Learn to ignore the rest. Read the Javadoc for String.substring().
14. See 13.
15. See 13. Read the Javadoc for String.length()
16. See 13. Read the Javadoc for String.replace()